1. Field of the Invention
The present invention relates to a translucent solar cell and a manufacturing method thereof, and more particularly, to a translucent solar cell which has improved light transmissibility and can avoid short-circuit during a manufacturing process thereof.
2. Description of Related Art
Thin-film solar cells include various thin films deposited on a substrate. These thin films are partitioned by laser-cutting into a number of individual and series-connected unit cells. The thin films deposited on the substrate sequentially includes, in a bottom-up direction, a front electrode layer, a photoconductive layer and a back electrode layer. The front electrode layer can be made of SnO2, ITO, ZnO, AZO, GZO, IZO, etc. The photoconductive layer can be made of IV group semiconductors or III-V, II-VI or I-III-VI group compounds. The back electrode layer can be made of Ag, Al, or Cr.
In general, the front electrode layer may be formed by sputtering or chemical vapor deposition (e.g. APCVD or LPCVD). The photoconductive layer may be formed by plasma-enhanced chemical vapor deposition (PECVD). The back electrode may be formed by sputtering or physical vapor deposition (PVD). In the prior art of translucent solar cell, U.S. Pat. No. 4,795,500 discloses a solar cell, as shown in FIG. 1A. The solar cell includes a substrate 1, a photoelectric conversion element 2 (including a front electrode layer 3, a photoactive layer 4 and a back electrode layer 5), and a resist layer 8. In fabricating the solar cell, the resist layer 8 is used as a mask in an etching process to form a desired light-transmissive region 6.
Besides, U.S. Pat. No. 6,858,461 discloses another solar cell. Referring to FIG. 1B, the solar cell 110 includes a substrate 114, a front electrode layer 118, a photoactive layer 120 and a back electrode layer 122. A plurality of transparency scribes 140 are formed on the solar cell 110 by laser cutting in a direction perpendicular to the grooves 128 for partitioning the solar cell into separate and series-connected unit cells 112. Meanwhile, the metal back electrode layer 122 is removed to form a light-transmissive region, so that a light source 116 can transmit through the solar cell module 110, thereby producing a transparent effect. In addition, U.S. Patent Publication No. 2006/0112987 discloses another solar cell (not shown), which employs a laser to remove a back electrode layer or the back electrode layer and a photoconductive layer to create a plurality of holes, such that a plurality of light-transmissive regions are formed over the entire solar cell module to produce a transparent effect on the entire solar cell module.
In the prior art cited above, while forming the light-transmissive regions, no matter whether a laser or an etching process is used to remove the film material such that holes or scribe lines are formed on the film layer, incomplete removal of film material from the holes or scribe lines can easily occur when the film layer is being cut due to a thermal effect, thus causing bridging of the conductive layers and hence a short-circuit therebetween. In addition, if the region to be removed is a hole, and given that the hole size is rather small, a large number of holes must be formed to produce a translucent solar cell module which allows light to transmit therethrough. As a result, each time the film material is removed during the process, the risk of having a short-circuit increases. And the occurrence of short-circuit can be reduced only by reducing the number of times of film material removal. Furthermore, if a laser is used, variation of the shape and size of the resulting hole is limited due to the limitation of laser beam itself. If holes of different shapes or of a larger size are desired, a laser with higher specification or higher power is required, thus increasing the manufacturing cost.